1. Field of the Invention
The present invention relates to a scroll compressor for compressing fluid, such as air or refrigerant gas.
2. Description of the Prior Art
FIG. 9 shows the whole structure of a conventional scroll compressor. In the figure, numeral 101 denotes an electric motor for driving a crankshaft 102. The crankshaft 102 is rotatably supported by a support member 107 via a bearing at its one end wherein the crankshaft 102 is provided with an eccentric engaging portion 103. The eccentric engaging portion 103 receives therein a shaft portion 105 of an orbiting scroll 104 via an eccentric bearing. The orbiting scroll 104 is prevented from rotation on its axis by an Oldham's ring 106, as a rotation preventing member, interposed between the orbiting scroll 104 and the support member 107, while it makes a swing motion or an orbital motion depending on the rotation of the crankshaft 102 via the shaft portion 105 thereof.
The orbital motion of the orbiting scroll 104 causes compression chambers 108 formed between a spiral vane of the orbital scroll 104 and a spiral vane of a fixed scroll 113 to move toward the center of the spiral vanes and reduce their volumes to thereby compress fluid introduced via a suction port. The compressed fluid is then discharged from the center of the fixed scroll 113.
A seal member 114 is disposed between the orbiting scroll 104 and the support member 107 to define an inner region surrounding the shaft portion 105 of the orbiting scroll 104 and an outer region communicating with the foregoing suction port.
Lubricating oil is drawn up from a lubricating oil storage 110 by a trochoid pump 109 and passes through a through hole 111 of the crankshaft 102 to reach the foregoing inner region. In the inner region, a portion of the lubricating oil is fed to the eccentric bearing disposed between the shaft portion 105 of the orbiting scroll 104 and the eccentric engaging portion 103 of the crankshaft 102 and then to the bearing disposed between the eccentric engaging portion 103 and the support member 107 and then returned to the lubricating oil storage 110. The other portion of the lubricating oil passes through an oil-feed passage formed in the orbiting scroll 104 to reach a lower part of the foregoing outer region. The oil-feed passage includes therein a restrictor 112. In the outer region, the lubricating oil is fed to the Oldham's ring 106 and a sliding portion between the orbiting and fixed scrolls 104 and 113 for lubrication thereof.
However, since the foregoing oil-feed passage extends downward and opens to the lower part of the outer region, it is difficult for the lubricating oil to go up to an upper portion of the Oldham's ring 106 due to the gravity. This causes a large frictional loss at an upper sliding portion between the Oldham's ring 106 and the support member 107, thus lowering the compressor efficiency and further inducing an occurrence of seizure. The Oldham's ring 106 and the support member 107 are made of the same material.
In addition, the lubricity at the sliding portion is largely lowered when using an HFC refrigerant and an ester oil as lubricating oil, as compared with the lubricity when using an HCFC refrigerant and a mineral oil as lubricating oil. Thus, an occurrence of seizure is more liable in recent air conditioners and the like.
FIG. 10 is a perspective view of the Oldham's ring 106. The lubrication of the sliding portions between the Oldham's ring 106 and the support member 107 is performed by using the lubricating oil in the neighborhood of the sliding portions. However, with key portions 115 having the shown shape, the Oldham's ring 106 does not work well for effectively introducing the lubricating oil to the sliding portions.